trying to create this texture with blender for 3d printing
You can use the Tissue add-on for this.

Create a quad mesh with the contours you want, then create a tile object that is a pit.

Select the tile object, then the contour object and press the Tessellate button. A new mesh will created with your perfect pits where each quad face was.

You'll want to keep the Scale value low, and enable the Merge option so each tile will be connected.



You can then smooth the shading and add a SubSurf modifier to get something very close to your reference photo.